In connection with a behavioral study on the functions of the paleostriatum an attempt is being made to prevent the development of the the overlying dorsal ventrical ridge by the intracleidoic application of methylazoxymethanol (MAM, a nucleic acid alkylating agent) in chickens (Gallus gallus). For this investigation, information is needed regarding the effect of MAM at critical times in neurogenesis. A special protocol involving the combined use of MAM and 3H-thymidine is being used for this purpose. In addition, a study of neutorgenesis in the Pekin duck (Anas plathyrhynchos) has been initiated.